Kyles will be busy on the summer weekends especially when floating season is in full swing, but it's still a beautiful campground.  During that time try and get a site away from the launch/takeout spots.  There are several good outfitter options nearby to make the float trip easy.

The road from the highway down into the campsite is inexplicably poor given the traffic this gets.  Not sure if it's because it's part federal and part county, but you would think they'd maintain it better or, to be really optimistic, pave it.  It's passable in any vehicle if you take your time, but be prepared.

Some great hikes from Kyles, the most spectacular being Eye of the Needle.  Easier ones include Twin Falls.  The definitive guide for hiking in the area is Tim Ernst's Buffalo River Hiking Trails.

I travel with 4 kids usually, and Kyles is a great spot for a number of family activities.  Cell service is minimal to nonexistent, so it also reduces screen time and gets the teenagers re-engaged!